1. Field of the Invention
This invention relates to an apparatus and a method of manufacturing a crystal, especially an apparatus and a method which are effective to increase the productivity of a crystal.
2. Description of the Prior Art
Czochralski Method (hereinafter referred to as "CZ Method") is known as a manufacturing method of a single crystal of silicon. In the CZ Method, a seed crystal is dipped on the melt which is formed by melting the polycrystalline ingredient, and the seed is lifted to growth the crystal thereunder.
In the CZ Method, crystal defect called "dislocation" is generated at the dipped portion. Such dislocation causes quality deterioration. Therefore, a contraction process called "necking" has been performed to form the neck having predetermined length. As a result, the dislocation can be prevented from entering the crystal.
During the necking, however, the slender neck portion which has been contracted can be broken due to its slender diameter. In this manner, when the break is caused during necking, the necked portion must be melted again, and it is necessary to do the pulling operation all over again.
Additionally, in the case of melting the neck portion, the temperature of the melt must be raise. As a result, a suitable thermal environment for the crystal growth is lost. Therefore, temperature adjustment is necessary when the pulling operation is done over from start.
However, this temperature adjustment is a complicated operation and it takes much time. A smooth crystal manufacturing cannot be achieved by having adjusted the temperature and melted the neck portion whenever the necking fails. This causes the productivity of crystal to reduce.